Empiric Earth CityStream Work Zones measures the second half of that equation: what the road actually shows, right now, from the cameras that just drove past it.
The finding
A work zone detection in CityStream expires after 24 hours if no camera sees it again. A road sign is kept for 30 days or longer. That difference is the measurement decision: work zones are transient, so the system tunes its memory to how long the object is expected to persist. A detection stays live only while cameras keep re-seeing it, and vanishes when they stop.
The result is that the map you look at shows work that is on the road today, not work that was on the road last week and no one updated.
Why permit data alone is not enough
The gap between paperwork and pavement is what CityStream customers report hearing. Permit records may show a work zone scheduled for a given date, and in practice that is not what happens on the road. There is a difference between what the system holds and what a driver actually meets.
The noisier problem is that cones are everywhere. They sit on US roadsides all the time without marking real road work, including cones holding a parking space or a spot on a sidewalk. Counting them all tells you nothing.
CityStream Work Zones handles the noise by assembling scattered detections into the road segments a work zone actually affects, instead of leaving isolated pins on a map.
How the measurement works
Cameras that see a road every day are the sensor. AI inference runs on the camera itself, not in the cloud, which is what makes a live view possible at all. A detection appears within a couple of seconds of being seen, and the image follows within a couple of minutes once it clears the upload quality threshold.
Every detection is indexed into H3 hexagons, the standard grid that divides the map into equal hexagonal cells, and map-matched to an OpenStreetMap node so it lands on the nearest road. Repeat sightings of the same object aggregate at H3 resolution 12.
Alongside the live view, curated products run on a weekly cadence. The curated traffic sign product returns better sign position and better sign meaning than a raw live detection does, because it aggregates many sightings before it decides.
The clock on each object class is set from real observation of how long that class of object usually persists on a road. A work zone object defaults to 24 hours. A road sign holds for 30 days or longer. Those numbers are the product, and they are only knowable by someone measuring the same roads repeatedly.
Only we know
The 24-hour work zone expiry is a measurement decision, not a storage policy. Setting it required knowing how often a work zone object gets removed and how often it stays past its permit. That distribution is not published anywhere. It is visible only to a network of cameras that pass the same road often enough to see both the arrival and the disappearance of the object, and to a product owner willing to tune expiry per object class rather than adopt a uniform retention policy.
What it means for the DOT and the map maker
Every detection ships with the image that produced it, and customers use that image as visual evidence of what was seen on the road. Mapping teams use the imagery to update their own map data after a construction project or another change alters a road.
Access is through a web interface and through APIs, so the same live feed can drive a dashboard for a traffic engineer or feed a downstream pipeline for a mapping team.
Both consumer and fleet cameras in the sensor network run the edge inference. The network's coverage is easiest to read directly off the live map view itself, which is described honestly as a sample of the data rather than the whole of it. Detection density is highest in New York City in current demos.
Limits
CityStream turns what road-facing cameras see into data products for public-sector and mapping customers. That is what it does; two things are worth saying about what it does not.
First, a detection can disappear for two reasons: the object was removed, or the network stopped passing that way. Absence is not evidence of removal, and the same map view can show a cleared work zone or a coverage gap the same way.
Second, no mile count, no city count, and no monthly detection volume for CityStream appear anywhere in the source evidence this piece is built from, so none appears here. Coverage varies, and less populated areas carry thinner history. What we show instead is the live map itself.
FAQ
Q: How fast does a new work zone show up in CityStream? A: A detection appears within a couple of seconds of the camera seeing it, and the image follows within a couple of minutes once it meets the upload quality threshold.
Q: What is work zone detection? A: A work zone detection is a recognized sign, cone or barrier that indicates road work, produced by AI running on a road-facing camera.
Q: How is CityStream different from a permit database? A: A permit database records the intended state of the road. CityStream records the observed state, from cameras on the road, and reports it back in seconds.
Q: How long does a work zone stay on the CityStream map? A: A work zone object has a default lifetime of 24 hours and vanishes if no camera sees it again. A road sign is kept 30 days or longer.
Q: Can I get the raw feed? A: CityStream is available through a web interface and through APIs.